Light-emitting diodes (LEDs) have become a new generation of green light sources with their long life, high light efficiency, and environmental friendliness. At present, LED not only replaces a common existing light sources in the traditional lighting field, but may also gradually be applied in applications with higher dimming requirements, such as backlight illumination in a liquid crystal display (LCD). When designing a load current adjusting circuit for the LED, a load current flowing through the LED may be adjusted in order to achieve dimming of the LED.